Configuring Network Routing

The system provides a single IP routing table. When an IP packet is sent to a given destination, the system selects the route whose destination most closely matches the packet's destination address, subject to the system's multihoming policy. See Multihoming Policy.

The system uses the information in the routing entry to determine which IP interface to send the packet on and, if the destination is not directly reachable, the next-hop gateway to use.

If no routing entries match the destination, the packet is dropped.

If multiple routing entries are equally close matches, and are not otherwise prioritized by multihoming policy, the system will load-spread across those matching entries on a per-connection basis.

The system does not act as a router.

The routing table has the following properties for each route.

Table 2-8 Route Properties

BUI Property	CLI Property	Description
Destination	destination and mask	Range of IP destination addresses (in CIDR notation) that can match the route. A routing entry with a Destination value of 0.0.0.0/0 matches any packet (if no other route matches more precisely), and is known as a Default route. In the Insert Static Route dialog in the BUI, you can select Default or Network as the value of Kind of route.
Gateway	gateway	Next hop (IP address) to send the packet to, except for routes that are type system.
Family	family	Internet protocol: IPv4 or IPv6
Type	type	Origin of the route: static, dynamic, dhcp, system, or direct.
Status	status	Route status: active or inactive. Inactive status applies to a static or direct route associated with a disabled or offline IP interface.
Interface	interface	IP interface the packet will be sent on. If an IPMP interface is specified, then one of the active IP interfaces in the IPMP group will be chosen randomly on a per-connection basis and automatically refreshed if the chosen IP interface subsequently becomes unusable. Conversely, if a given IP interface is part of an IPMP group, it cannot be specified in the Interface property because such a route would not be highly available.

Routing entries come from a number of different origins, as identified by the Type property. Although the origin of a routing entry has no bearing on how it is used by the system, its origin does control whether and how it can be edited or deleted. The system supports the following types of routes.

Table 2-9 Supported Route Types

Type	Description
Static	Created and managed by the appliance administrator. See Adding a Static Route - BUI, CLI.
Dynamic	Created automatically by the appliance via the RIP and RIPng dynamic routing protocols (if enabled).
DHCP	Created automatically by the appliance part of enabling an IP interface that is configured to use DHCP. A DHCP route will be created for each default route provided by the DHCP server.
System	Created automatically by the appliance as part of enabling an IP interface. A system route will be created for each IP subnet the appliance can directly reach. Since these routes are directly reachable, the "gateway" field instead identifies the appliance's IP address on that subnet.
Direct	Created and managed as a network interface property: Directly Reachable Network(s). Directly reachable subnet that the local IP address is not a member of, but to which the datalink of its interface is physically connected. This improves scalability by conserving IP addresses, and could ease traffic congestion through core switches and routers. Direct routes are configured as network interfaces by using the Configuration: Network: Configuration BUI screen or the configuration net interfaces CLI context.